1. FIELD OF THE INVENTION
This invention relates to the harvesting of grain and seed crops of the kind that are conventionally harvested by means of a combine harvester. More particularly, the invention relates to systems, methods and apparatus for harvesting such crops.
2. DESCRIPTION OF THE PRIOR ART
The applicant herein has already disclosed a novel method of and apparatus for harvesting grain and seed crops that provide an alternative to the use of conventional combine harvesters. In this regard, reference is made to U.S. Pat. No. 5,794,423 issued on Aug. 18, 1998; U.S. Pat. No. 5,795,222 issued on Aug. 18, 1998; and U.S. Pat. No. 5,873,226 issued on Feb. 23, 1999; all of these patents having been assigned to McLeod Harvest Inc. and are referred to collectively in the following description as xe2x80x9cthe McLeod patents.xe2x80x9d
A conventional combine harvester operates by carrying out all of the harvesting steps in the field on a continuous basis. The crop plants are cut, the cut plants are threshed to separate grain (or seeds such as peas, etc.), chaff and (inevitably) weed seeds from the stalks, the grain is then cleaned by separating it from the chaff and weed seeds, the grain is delivered to a waiting collection vehicle, and the stalks, chaff and weed seeds are returned to the field. The disadvantages of this are that (a) combine harvesters are very expensive to purchase and to operate; (b) they are not very efficient at cleaning the grain, so some grain is lost and/or further grain cleaning is required; and (c) chaff and weed seeds are returned to the field, so that their economic value is lost and weeds proliferate.
The concept underlying the systems disclosed in the above patents is that, instead of attempting to carry out all of the harvesting steps in the field, only the step of threshing and removing stalks is carried out, and the remaining product (a mixture of grain, chaff and weed seedsxe2x80x94referred to by the coined word xe2x80x9cgraffxe2x80x9d) is collected and transported to a fixed grain cleaning site. The advantage of this is that the harvesting equipment may be less complicated and expensive than a conventional combine harvester, the cleaning of the grain may be carried out more efficiently at a fixed site, the economic value of the chaff and weed seeds may be realized, and the need for herbicides is reduced (because the weed seeds are collected rather than being returned to the field).
It has been found that this system is extremely effective, but inconveniences have been encountered in that graff has proven to be a difficult material to handle and process. Since graff contains a large percentage of chaff, it is bulky for its weight and it is quite fibrous in composition. Unlike grain collected by a combine harvester, graff does not easily xe2x80x9cflowxe2x80x9d from containers and it is difficult to move by conventional means, such as augers, because it bridges or binds within itself and does not flow internally to replace material that has been removed from the bottom of a container or pile of the material. In general, it can be said that graff tends to pack, clump, bridge, rat-hole and bind, rather than flow smoothly. This causes problems not only when the graff is stored in silos or the like before it is processed, but also causes difficulties of material flow within the harvesting device and transportation vehicles.
Moreover, graff is difficult to store because, if stored in the open, it tends to blow away and also to spoil if it gets wet. However, if stored in a container, it is difficult to remove for the reasons mentioned above.
Additionally, there is a need to improve the overall efficiency of the system generally and to improve the manner in which individual components operate in order to increase the economic competitiveness of the system with conventional harvesting systems.
An object of the invention is to improve the efficiency and to reduce the equipment cost of carrying out a grain harvesting method of the type disclosed in the patents mentioned above.
Another object of the invention, at least in its preferred forms, is to overcome difficulties caused by the poor flow properties of graff.
Another object of the invention, at least in broader aspects, is to optimize a grain harvesting system as opposed to a single grain harvesting machine such as a conventional combine harvester.
Another object of the invention is to reduce the operational cost of carrying out a grain harvesting method of the type disclosed in the patents mentioned above.
Another object of the invention, at least in its preferred forms, is to improve the effectiveness of the harvesting unit used to separate the graff from the crop stalks in the field.
Another object of the invention, at least in its preferred forms, is to improve the effectiveness of the grain cleaning mill used to separate grain from the remainder of the graff at a fixed site and to process crop the residue.
According to one aspect of the invention, there is provided a method of harvesting and cleaning a plant crop, wherein the crop is cut from a field area and threshed in a mobile harvesting unit to produce stalks that are returned to the field area and xe2x80x9cgraffxe2x80x9d, a mixture including grain, chaff and weed seeds, which is collected within the harvesting unit; the collected graff is transferred periodically from the harvesting unit to at least one vehicle and transported by said at least one vehicle to a cleaning mill, and the graff is cleaned by the cleaning mill to produce a cleaned grain product and xe2x80x9cmillingsxe2x80x9d, a mixture including chaff and weed seeds. To avoid problems caused by the poor flow characteristics and very low density of graff, the method is operated to avoid storage of the graff prior to cleaning by the cleaning mill.
What we mean by avoiding storage of the graff prior to cleaning is that the graff is not transferred to any temporary storage container or storage pile from the time it is produced by the harvester to the time it is cleaned by the cleaning mill. The graff is held only in the harvester unit and the vehicle, and is fed immediately into the cleaning mill. Consequently, the use of stationary surge bins and the like at the cleaning mill or other area is specifically avoided. The graff is fed directly from the harvesting unit to the vehicle, and directly from the vehicle to the a receiving unit for the cleaning mill from which it is fed substantially immediately and completely into the cleaning mill.
Thus, according to another aspect of the present invention, there is provided a system for harvesting and cleaning a plant crop, which includes a harvesting unit for cutting a crop from a field area and for threshing the cut crop to produce stalks that are returned to the field area and xe2x80x9cgraffxe2x80x9d, a mixture including grain, chaff and weed seeds, which is collected within the harvesting unit; at least one vehicle for receiving collected graff from the harvester unit when the harvesting unit is at least partially full, and for transporting the graff to a cleaning mill; and a cleaning mill located at a site (yard area) remote from the field area, for cleaning the graff to produce a cleaned grain product and xe2x80x9cmillingsxe2x80x9d, a mixture containing chaff and weed seeds. The system specifically excludes and avoids the use of any device for storage of the graff prior to cleaning of the graff in the cleaning mill.
According to another aspect of the invention, there is provided a stationary cleaning mill for graff, comprising an entrance (usually located at an elevated position) for the graff, screening apparatus for separating grain from the graff to produce cleaned grain and millings, and separate outlets for the cleaned grain and millings. The cleaning mill includes a receiving unit for the graff for feeding the graff to the entrance of the graff cleaning mill, the receiving unit being sized to permit a graff delivery vehicle to drive into the receiving unit to transfer an entire vehicle load of graff to the receiving unit by a direct dumping operation of the entire vehicle load.
In another aspect, the invention provides a stationary cleaning mill for graff, comprising an entrance (usually located an elevated position) for the graff, screening apparatus for separating grain from the graff to produce cleaned grain and millings, and separate outlets for the cleaned grain and millings. The cleaning mill includes a material-conveying fan at the outlet for the millings, the material-conveying fan impacting the millings to cause at least partial crushing or breaking of weed seeds in the millings, removing the millings from the cleaning mill, and propelling the millings through the outlet for the millings.
According to yet another aspect of the invention, there is provided a mobile harvesting unit for harvesting graff, including a wheeled harvester body and a harvesting header at the front of the harvester body for cutting a crop from a field area, the harvester body containing a threshing unit for the cut crop for separating stalks from graff, a discharge for discharging separated stalks back to the field area, and a storage tank for storage of the separated graff. The harvesting unit includes an elongated hitching arm having opposite lateral ends for connection at one end to the harvester body and at an opposite end to a rear portion of a propulsion device, the hitching arm having a raised section intermediate the opposite ends passing over and clear of the harvesting header.
According to yet another aspect of the invention, there is provided a hitching arm for a graff harvester, comprising a rigid elongated element having two opposite ends for connection, respectively, to the graff harvester and to a propulsion device. The arm has upwardly extending sections extending from each opposite end towards a centre of the hitching arm, and an elevated centre section.
According to still another aspect of the invention, there is provided a receiving unit for graff, for feeding graff to an elevated entrance of a graff cleaning mill, including a receptacle for graff and a conveyor for raising graff from the receptacle to the elevated entrance. The receptacle is sized to permit a graff delivery vehicle to drive into the receptacle and to deposit an entire vehicle load of graff into the receptacle by a direct dumping operation.
Preferably, the invention may provide a method of harvesting and cleaning a plant crop, wherein the crop is cut from a field area and threshed in a mobile harvesting unit to produce stalks that are returned to the field area and graff, a mixture of threshed grain kernels, chaff and weed seeds, which is collected within the harvesting unit, the collected graff is transferred to a vehicle when the harvesting unit is full, the graff is transported by the vehicle to a cleaning mill located in a yard area remote from the field area, and the graff is cleaned automatically by the cleaning mill to produce a cleaned grain product and a mixture of chaff and weed seeds, wherein a capacity of the harvesting unit to hold graff is made the same as or smaller than a capacity of a vehicle used for the delivery, the rate of cleaning of the graff by the cleaning mill is made the same as or higher than a rate of graff output from the field area averaged over several cycles of filling and emptying the harvesting unit and transfer to the vehicle, and the number and speed of operation of the vehicles is made high enough to avoid substantial waiting periods between filling of the harvesting unit with graff and transfer of the collected graff to the vehicle.
Preferably, the capacity of the harvesting unit is substantially the same as the capacity of the vehicle, and a single vehicle is provided for transporting the graff.
It is also preferable that the capacity of the cleaning mill to hold and process graff is no less than the capacity of the vehicle to transport graff from the field area to the cleaning mill, and the rate of cleaning of the graff by the cleaning mill is about the same as the rate of graff output from the field area.
In another preferred form, the invention provides a system of harvesting and cleaning a plant crop, which comprises: a harvesting unit for cutting a crop from a field area and threshing the cut crop to produce stalks that are returned to the field area and xe2x80x9cgraffxe2x80x9d, a mixture of grain, chaff and weed seeds, which is collected within the harvesting unit, a vehicle for receiving collected graff from the harvester unit when the harvesting unit is full, and for transporting the graff to a cleaning mill; and a cleaning mill located in a yard area remote from the field area, for cleaning the graff to produce a cleaned grain product and xe2x80x9cmillingsxe2x80x9d, a mixture of chaff and weed seeds, wherein a capacity of the harvesting unit to hold graff is made the same as or smaller than a capacity of a vehicle used for the delivery, a rate of cleaning of the graff by the cleaning mill is made the same as or higher than a rate of graff output from the field area averaged over several cycles of filling and emptying the harvesting unit and transfer to the vehicle, and a number and speed of operation of the vehicles is made high enough to avoid substantial waiting periods between filling of the harvesting unit with graff and transfer of the collected graff to the vehicle.
In another preferred aspect, the invention relates to a mobile harvesting unit for harvesting graff, comprising a harvesting header (e.g. a direct-cut or swath pick-up type) at a front of the harvesting unit for removing a crop from a field area, a threshing unit for separating stalks from a mixture graff, a mixture of grain, chaff and weed seeds, a storage tank for storage of the separated graff, and a hitching arm for connection to a rear portion of a propulsion device, the hitching arm being of inverted generally U-shape to allow attachment at opposite ends of the arm to the unit and the propulsion device while extending over the harvesting header.
In the harvesting unit of this kind, the hitching arm preferably supports and guides a mechanical driveling for transferring mechanical power from the propulsion device to the harvesting unit, the driveline including a plurality of rotary shafts joined by constant velocity joints or U-joints to allow the driveline to adapt to changes of direction of the hitching arm. The hitching arm may also be used for guiding and protecting hydraulic tubes for conveying hydraulic fluid under pressure from the propulsion device to the harvesting unit. These tubes may pass through an interior channel in the hitching arm.
In another preferred aspect, the invention relates to a mobile harvesting unit for harvesting graff, comprising a cutting head, a threshing unit for separating stalks from graft, a mixture of grain, chaff and weed seeds, a storage tank positioned above the threshing unit for temporarily storing graff, an auger bed for transporting graff to collection areas on opposite lateral sides of the unit, and a pair of graff elevators, one on each side of the storage tank, for simultaneously removing graff from the collection areas of the auger bed and for delivering removed graff to a top of the storage tank.
Further, the invention in another preferred aspect relates to a cleaning mill for graff, comprising a receiving unit for graff sized to allow a graff transportation vehicle to drive at least partially therein for dumping a load of graff, a graff conveyor for feeding graff into the mill as a moving matted layer of approximately constant thickness (preferably in the range of 1.5 to 3 inches), and elevators for tilting the receiving unit, following removal of the vehicle, to cause the load of graff to slide to the graff conveyor.
Further, in another preferred aspect, the invention relate to a cleaning mill for graff, comprising an aspirator for blowing air through a falling matted layer of graff to remove chaff and light materials leaving aspirated graff containing grain kernels and heavy materials, a centrifugal separator for removing the chaff from the air after passing through the curtain of graff, a fan and ductwork for recirculating air continually through the curtain of graff and through the separator, a screening unit for separating grain from remaining materials from the aspirated graft, an outlet for the separated grain, a mill for milling the remaining materials to produce millings, ductwork for circulating the millings to the centrifugal separator, an outlet device for removing solids from the centrifugal separator for discharge from the mill.
It will be appreciated that, in the following discussion, the reference to xe2x80x9cgrain kernelsxe2x80x9d or xe2x80x9cgrainxe2x80x9d as the desired product of the harvesting operation should be taken to include the grain kernels or seeds of all crops that are harvestable by conventional combine harvesters, not merely wheat. Such products include, for example, oats, barley, peas, lentils, rice, soybeans, mustard seed, canola, rapeseed, etc. The harvesting system of the present invention can be operated with all such crops.
Moreover, while the grain kernels are separated from the graff to leave a mixture of chaff, weed seeds and other materials, referred to as millings, the components of the millings may themselves, if desired, be separated either during the cleaning of the grain in the cleaning mill, or subsequently. Separate outlets may be provided for the separate components of the millings. Thus, while the claims of this application may refer to an outlet for millings, there may in practice be two or more outlets for various components of the millings, and the term used in the claims is intended to cover this eventuality.
It will also be understood that the millings may contain additional elements such as unthreshed heads, pieces of straw, dust, leaves, and other harvesting residues and debris, and so the term should not be limited merely to a mixture of weed seeds and chaff.
In the following description, numerical values are often expressed both in metric units and in non-metric units (the latter being shown in brackets). In the event of any discrepancy, the values expressed in non-metric units should be considered correct.